Does cold blood cardioplegia offer adequate oxygen delivery to the myocardium during coronary artery bypass grafting?
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Biological Transport, Active↗
Biomedical subjects
W Schmidt
Publications and source records attributed to W Schmidt.
Multiple parallel access in visual attention.
It is widely accepted that there exists a region or locus of maximal resource allocation in visual perception--sometimes referred to as the spotlight of attention. We have argued that even if there is a single locus of processing, there must be multiple loci of parallel access--several places in the visual field must be indexed at once and these indexes can be used to determine where attention is allocated. We have carried out a variety of studies to support these ideas, including experiments showing that subjects can track multiple independent moving targets in a field of identical distractors, that the enhanced ability to detect changes occurring on these targets does not accrue to nontargets nor to items lying inside the convex polygon that they form (so that a zoom-lens of attention does not fit the data). We have used a visual search paradigm to show that (serial or parallel) search can be confined to a subset of indexed items and the layout of these items is of little importance. We have also studied the phenomenon known as subitizing and have shown that subitizing occurs only when items can be preattentively individuated and in those cases location precuing has little effect, compared with when counting occurs, which suggests that subitizing may be carried out by counting active indexes rather than items in the visual field. And finally we have run studies showing that a certain motion effect that is sensitive to attention can occur at multiple precued loci. We believe that this evidence suggests that there is an early preattentive stage in vision where a small number of salient items in the visual field are indexed and thereby made readily accessible for a variety of visual tasks.
Attention↗
Role of vitamin B12 enzymes in platelet cell signalling, adhesion and aggregation.
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5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
[Antepartum monitoring and peripartal findings in mono- and dichorial twin pregnancy].
In a group of 65 twin pregnancies the difference of perinatal findings and antepartal test results was evaluated in relation to amnionicity and chorionicity. Monochorionic placentation was found in 33% of the pregnancies. The rate of foetal malformation (11%), neuromuscular dysfunction (6%), perinatal mortality (11%) and duration of neonatal intensive care was increased in those cases. The most useful diagnostic tool was B-Mode-ultrasound (first detection and surveillance of multiple pregnancy, especially diagnosis of inter-twin growth discordancy). Non stress test and Doppler sonography were found to be of value as additional tests for detection of functional differences between both twins. There were no differences between findings in first and second twin as well as between findings in pregnancies with mono- or dichorionic placentation.
Birth Weight↗
[HELLP syndrome--amaurosis in sinus thrombosis with complete recovery].
We report on a case of a 22-year old primigravida with HELLP syndrome in association with blindness and cerebral sinus thrombosis. The diagnosis of the cerebral sinus thrombosis was based on MRI 1h after delivery. Immediate caesarean section and intensive care treatment led to a complete recovery of the patient.
Adult↗
[PgE2 gel and PgE2 vaginal tablets for induced labor--a prospective randomized study].
In a prospective randomised study, the effects of an intracervical gel containing 0.5 mg PgE2 and an intravaginal tablet containing 3 mg PgE2 were compared in their efficiency to induce delivery at term. When only gel was used, induction failed in 45% of the cases, especially with an initially immature cervix score. However, these patients did show significant improvement of the Bishop score. The vaginal tablet was more effective with regard to the induction of delivery. When using the vaginal tablet alone, induction failed in only 5% of cases (p < 0.001). Best results, however, were obtained with a combination of both application forms. In this group there were no failures. Tablet application induced delivery within 24 hours in 56% of the cases, gel application in only 27% (p < 0.001). There were no significant differences observed in these groups during the course of labour. The length of the latency period was identical, whether a tablet or a gel was used in initiating labour. In 29% of the cases, beta-sympathicomimetics had to be used because of tetanic contractions or polysystolia. No significant differences in the occurrence of these contractions were seen in either the gel or the tablet group. Even in a high-risk collective with 25% pathological Doppler-flow findings, no higher rate of operative deliveries or fetal acidoses was observed after prostaglandin induction, if careful surveillance of the patients and early use of tocolytics in experienced hands were administered. Our results further confirm the concept of a differential induction of labour with prostaglandins.(ABSTRACT TRUNCATED AT 250 WORDS)
Administration, Intravaginal↗
[Premature separation of the placenta--clinical findings and fetal monitoring].
In a study group of 41 pregnant women of postpartally confirmed placental abruption, the prognostic value of clinical and diagnostic findings was investigated. The incidence of placental abruption was 1.4% of all deliveries within a three-year interval. 51% of patients showed vaginal bleeding before delivery. Retroplacental haematoma was found in 49% of cases ultrasonographically. A total of 75% had a pathological CTG test. More than 95% of these findings occurred within 3 days before delivery. Abnormal Doppler flow findings in foetal vessels more than 3 days before delivery were seen in 62% of cases. In the last three days before delivery, 86% were abnormal. Preterm delivery before 37 weeks of gestation was registered in 82% of patients. Perinatal mortality amounted to 12%. The rate of severely dystrophic newborn was 30%. Even in cases with lack of the clinical and/or sonographical findings, the possibility of placental abruption should be considered, if an acute deterioration of cardiotocographic or Doppler-sonographic findings.
Abruptio Placentae↗
[Umbilical cord entanglement and color-coded Doppler ultrasound].
The incidence of umbilical cord entanglement is about 20-33%. The present study describes the antepartal detection of nuchal cord using Colour Doppler sonography. In 137 cases, the identification of cord entanglement through a high resolution real-time Colour Doppler equipment (Picker 192/Acuson 128 XP) was achieved with sensitivity of 97%, the positive predictive value was 89%, the negative predictive value 96% and the efficiency 93%. In complicated cases, the pulsed Doppler sonography of the cord vessels provided significant differential diagnostic evaluation (Aa. and V. umbilicales vs. uteroplacental vessels). The use of this new method is especially indicated in situations with uncertain variable decelerations and/or other abnormal findings in the antepartal FHR-registration. The early recognition of a nuchal cord could possibly prevent serious peri-/subpartal complications in many cases. The result of our investigations suggest, that once a cord entanglement has been identified sonographically, the antepartal cardiotocography, sonography, Doppler flow examination and intrapartal foetal monitoring should be more frequently and intensively performed.
Apgar Score↗
Serum carotene deficiency in HIV-infected patients. Berlin Diarrhoea/Wasting Syndrome Study Group.
OBJECTIVE: To assess total serum carotene concentration in HIV-infected patients as an indicator of fat malabsorption in correlation with diarrhoea, secondary enteric infections, and blood lymphocyte subsets. DESIGN: Prospective study. SETTING: Two referral-based tertiary care centres in Berlin, Germany. PATIENTS: A total of 33 controls and 116 HIV-infected patients who had complete microbiological evaluation of stools and biopsies obtained at upper endoscopy because of diarrhoea (n = 54), or other symptoms (n = 62), were studied. MAIN OUTCOME MEASURES: Total serum carotene concentration was determined spectrophotometrically. RESULTS: Total serum carotene concentration was abnormal (< 0.88 mumol/l) in 77% of HIV-infected patients and significantly decreased compared with controls [0.47 mumol/l (range, 0.06-1.69 mumol/l) versus 1.37 mumol/l (range, 0.88-2.92 mumol/l); P < 0.0001]. Total serum carotene concentration did not differ between AIDS patients and patients at earlier disease stages, between patients with or without secondary enteric infections, or between patients with or without fever. In patients at earlier disease stages, but not in AIDS patients, total serum carotene concentration was lower for patients with than without diarrhoea. The percentage of CD4 lymphocytes (r = 0.364; P < 0.001), CD4 count (r = 0.28; P = 0.0013), and CD4/CD8 ratio (r = 0.38; P < 0.001) in the peripheral blood correlated with total serum carotene levels in HIV-infected patients. CONCLUSION: HIV-infected patients frequently have abnormal total serum carotene concentrations indicating fat malabsorption which may contribute to diarrhoea. Furthermore, total serum carotene concentrations correlate with immunologic abnormalities in HIV infection.
CD4-Positive T-Lymphocytes↗
Abnormalities in subset distribution, activation, and differentiation of T cells isolated from large intestine biopsies in HIV infection. The Berlin Diarrhoea/Wasting Syndrome Study Group.
Intestinal T cells have a unique state of activation and differentiation which might specifically affect or be affected by HIV infection. Lymphocyte subsets in the peripheral blood are well characterized, but our knowledge about intestinal lymphocytes in HIV infection is incomplete. We therefore analysed lymphocytes isolated from large intestine biopsies of AIDS patients and controls by three-colour cytofluorometry. In the large intestine of HIV-infected patients CD4 T cells were reduced and CD8 T cells were increased compared with controls. Most of the CD8 T cells in the colorectal mucosa of AIDS patients were of the cytotoxic phenotype. Activated and resting CD4 T cells were similarly reduced, the expression of CD25 and HLA-DR of CD8 T cells was unaltered and increased, respectively. In intestinal CD4 T cells the expression of CD29 was decreased, but the expression of CD45RO and HML-1 was normal. CD8 T cells had a decreased expression of all these differentiation markers. Our findings demonstrate substantial alterations in subset distribution, activation, and differentiation of large intestine T cells, which may contribute to the secondary infections and malignancies commonly observed in the gut of AIDS patients.
Acquired Immunodeficiency Syndrome↗
Lung correction and mid plane irradiation dose factors in anatomic phantoms of proportional sizes.
In vivo dosimetry in combined anterior-posterior, posterior-anterior, total body irradiation (AP-PA TBI) with Co-60 units makes it possible to determine the absorbed dose (D) in the patient's mid plane by means of an entrance dose reading (R) multiplied by a Mid Plane Dose Factor (MDF) and a Lung Correction Factor (CF). A theoretical model of an anatomic phantom, based on a number of cylindrical ellipsoide which could be set in any order following a real therapeutical position, was established. The dimensions of the constituent parts were variable and subject to change. In this work, calculations in the reference phantom with volume VO were compared with measurements in two experimental anatomic phantoms of the same volume and shape; 1. a water phantom from the former investigations and 2. a polystyrene phantom based on real patients' CTs with the lungs' inhomogeneities. A generalisation to proportional phantom sizes with volume V was set up. It was found that in this approach the ratio V/Vo had a significant role in the determination of MDF and CF, when real scattering conditions, e.g. lack of scatter due to the finite phantom width, were included.
Humans↗
Genetic modification of cells by receptor-mediated adenovirus-augmented gene delivery: a new approach for immunotherapy of cancer.
Most concepts of gene therapy of cancer are based on the generation of an enhanced immune response against the cancer by means of vaccination with gene-modified cancer cells. We have investigated the applicability of a new gene transfer technique which uses the receptor-mediated endocytosis pathway and the endosome disruption activity of adenovirus for the generation of a cancer vaccine consisting of interleukin-2 (IL-2)-transfected, irradiated murine melanoma cells (clone M-3). This technique resulted in very high IL-2 expression (in the range of 30,000 Units IL-2/10(6) cells/24 hrs) in the transfected cells without the need to selection of stably expressing cell clones. We found that this high IL-2 expression of the melanoma cells correlates with high efficacy of the vaccine. Immunization of animals with this vaccine elicits a systemic T-cell-mediated immune response which protects from tumor development after implantation of highly tumorigenic doses of wild-type melanoma cells.
Adenoviridae↗
Breast cancer and prognostic factors. Tumour size, degree of differentiation, proliferation kinetics and expression of steroid hormone receptors.
In a group of 161 patients with operable cancer of the breast, tumour size, axillary node status and histopathological grading were correlated. Furthermore, steroid hormone receptor status was assessed both biochemically and immunohistochemically. The rate of Ki67-positive cells, the ploidy status and the S-phase fraction of the carcinoma, as assessed by means of flow-cytometry, were measured and correlated with tumour size and conventional histopathological grading. As expected, a significant correlation between tumour size and the frequency of axillary lymph node metastases was found (p < 0.00001). There was however, also a significant increase of undifferentiated cancers with increasing tumour size (p < 0.001). There was no correlation between steroid hormone receptor expression and grading but a slight decrease of immunohistochemically oestrogen receptor positive cancers with increasing tumour size (p < 0.02). On the other hand, there was a marked increase of both Ki67-score (p < 0.003) and S-phase fraction (p < 0.001) with increasing tumour size. Neither of the first two parameters correlated significantly with grading. The frequency of aneuploid tumours was dependent on tumour size (p < 0.05) as well as grading (p < 0.01). The findings point towards a change of biological properties of the cancer during the course of growth, such as histopathological dedifferentiation and increased proliferation fraction and frequency of aneuploid tumours. The expression of steroid hormone receptors however is virtually unchanged.
Aneuploidy↗
[Adaptation of peripheral microcirculation in the course of pregnancy].
The present prospective study investigates the changes of the peripheral microcirculation during pregnancy and puerperium, especially in preeclampsia. Using videocapillary microscopy we investigated 30 pregnant women at 4 different times. We studied red cell velocity as well as reactivity to artificial ischaemia of capillary blood vessels. An increase of red cell velocity during the course of pregnancy of approximately 30% and a reduction near normal values within 12 weeks after delivery was demonstrated. There is an obvious decrease of vascular reactivity to ischaemia as a consequence of increasing physiological vasodilatation in pregnancy. 24 pregnant pregnant women with normal peripheral microcirculation at the beginning of pregnancy had an uneventful pregnancy but 3 out of 6 pregnant women with an obviously impaired microcirculation developed pregnancy induced hypertension. These 3 were smokers.
Adult↗
Somatic gene therapy for cancer: the utility of transferrinfection in generating 'tumor vaccines'.
The last few years have seen the development of a branch of somatic gene therapy which aims at strengthening the immune surveillance of the body, leading to eradication of disseminated cancer tumor cells and occult micrometastases after surgical removal of the primary tumor. Such a tumor vaccination protocol calls for cultivation of the primary tumor tissue and the insertion of one of three types of genes into the isolated cultured tumor cells followed by irradiation of the transfected or transduced cells to render them incapable of further proliferation. The cells so treated constitute the 'tumor vaccine'. A review of the literature suggests that for mouse models, in the initial period after inoculation, rejection of the tumor cells is usually effected by non-T-cell immunity, whereas the long-term systemic immune response is based on cytotoxic T-cells. High expression of the gene inserted into the tumor cells may be critical for the success of the vaccination procedure. Examples are given which indicate that transferrinfection, a procedure to introduce genes by adenovirus-augmented receptor-mediated endocytosis, meets some important prerequisites for successful application of this type of gene therapy.
Animals↗
Failure of hyperfractionated radiotherapy to reduce bone growth arrest in rats.
PURPOSE: Radiotherapy of the craniospinal axis is causing an age dependent growth arrest in children. The purpose of this paper was to examine in an animal model, whether hyperfractionated radiotherapy, given with twice daily fractions in conventional overall treatment time, would cause less growth arrest of the spinal column than a regular treatment schedule. METHODS AND MATERIALS: The time-dose-fraction schedule for the treatment of the craniospinal axis of children with medulloblastomas was used as model for the treatment of the spine in rats. The entire spine of weanling rats received either 3570 cGy in 21 daily fractions of the 170 cGy, 5 times per week over 27 days, or 3630 cGy in 33 fractions of 110 cGy, given twice daily with 6-hr intervals over 21 days. RESULTS: Both fraction schedules were isoeffective and caused a growth inhibition of 9.5%. The growth arrest was complete after 1870-2420 cGy. The alpha/beta ratio for the growing rat vertebrae was 3400 cGy. This result contrasts with the growth sparing effect observed with hyperfractionation of accelerated treatment schedules. CONCLUSION: Growing bone is a fast proliferating tissue. Hyperfractionation with 110 cGy BID compared to 170 cGy given once a day, has no sparing effect on bone growth in rats if given in conventional overall treatment time.
Animals↗
Role of carrier ligand in platinum resistance of human carcinoma cell lines.
We have examined the effects of the cis-diammine and 1,2-diaminocyclohexane (dach) carrier ligands on cytotoxicity, platinum accumulation and efflux, platinum incorporation into DNA, cytotoxicity of Pt-DNA adducts, and repair of Pt-DNA adducts in the human ovarian carcinoma A2780 cell line, the human colon carcinoma HCT8 cell line, and their cis-diamminedichloroplatinum(II) (cisplatin)-resistant derivatives, A2780/DDP and HCT8/DDP. The A2780/DDP cell line was 7.7-fold resistant to cisplatin, and the HCT8/DDP cell line was 1.6-fold resistant to cisplatin compared to their parental cell lines. Both were considered as examples of acquired cisplatin resistance. The HCT8/S cell line was 4.6-fold resistant to cisplatin compared with the A2780/S cell line and was considered an example of intrinsic resistance. Decreased accumulation of cisplatin made a significant contribution to acquired cisplatin resistance in the A2780/DDP cell line, probably contributed to intrinsic resistance in the HCT8/S cell line, but made little or no contribution to acquired resistance in the HCT8/DDP cell line. Decreased cytotoxicity of Pt-DNA adducts made a major contribution to both acquired and intrinsic cisplatin resistance in all three cell lines. Increased repair activity made a significant contribution to the decreased cytotoxicity of Pt-DNA adducts in the HCT8/S cell line, a weak contribution in the A2780/DDP cell line, and no contribution in the HCT8/DDP cell line. Glutathione levels were elevated in all the cell lines with acquired and intrinsic resistance, but the increased glutathione levels were not associated with decreased incorporation of platinum into DNA. These data suggest that both decreased accumulation and increased repair contribute to cisplatin resistance to different degrees in these human carcinoma cell lines. In addition, mechanism(s) other than repair may contribute to the decreased cytotoxicity of cis-diammine-Pt-DNA adducts. Of the cells with acquired cisplatin resistance, the HCT8/DDP cell line showed no resistance to tetrachloro(trans-DL)1,2-diaminocyclohexaneplatinum(IV) (ormaplatin, formerly known as tetraplatin), while the A2780/DDP cell line was just as resistant to ormaplatin as to cisplatin. The intrinsically cisplatin-resistant HCT8/S cell line showed only partial cross-resistance to ormaplatin. The effects of the dach carrier ligand on both acquired and intrinsic resistance in these cell lines appeared to occur primarily at the level of cytotoxicity of dach-Pt adducts, but the differences in the cytotoxicity of cis-diammine-Pt and dach-Pt adducts could not be explained by differences in repair of those adducts.(ABSTRACT TRUNCATED AT 400 WORDS)
Antineoplastic Agents↗
A high-field superferric NMR magnet.
Strong, extensive magnetic fringe fields are a significant problem with magnetic resonance imaging magnets. This is particularly acute with 4-T, whole-body research magnets. To date this problem has been addressed by restricting an extensive zone around the unshielded magnet or by placing external unsaturated iron shielding around the magnet. This paper describes a solution to this problem which uses superconducting coils closely integrated with fully saturated iron elements. A 4-T, 30-cm-bore prototype, based on this design principle, was built and tested. The 5 G fringe field is contained within 1 meter of the magnet bore along the z axis. Homogeneity of the raw magnetic field is 10 ppm over 30% of the magnet's diameter after passive shimming. Compared with an unshielded magnet, 20% less superconductor is required to generate the magnetic field. Images and spectra are presented to demonstrate the magnet's viability for magnetic resonance imaging and spectroscopy.
Magnetic Resonance Spectroscopy↗